Patent GB-489852-A (GB)
Title: Hydraulic drive for machine tools
IPC: B23Q5/033
Filed: 1937-02-02
Abstract: 489,852. Hydraulic transmission of power. KLOPP, F. Feb. 2, 1937, No. 3089. Convention date, Feb. 13, 1936. Addition to 471,201. [Class 69 (ii)] An improvement in the control mechanism of the parent Specification consists in that, simultaneously with the closing of the outflow from one side of the working cylinder, the auxiliary control slide admits pressure fluid from the pump to the main control slide in a direction to assist the effect of the accumulated pressure to which the main slide is subjected due to the closure of the outflow from the working cylinder, while simultaneously with the opening of the outflow from the same side of the working cylinder the auxiliary control slide admits pressure fluid from the pump to the main control slide in a direction to assist the effect of the spring. Another improvement consists in that that side of the operating cylinder to which the supply of pressure fluid is initiated by the spring, is shut off from the outflow to the pressure fluid reservoir by the auxiliary control slide substantially at the moment when the auxiliary control slide opens the connection between the other side of the operating cylinder and the pressure fluid reservoir. When the valves 78, 79, 80 occupy the positions shown in Fig. 1, the machine part 155 is moved to the left on a working stroke. Pressure liquid from the pump passes by channel 41, port 42, annular chamber 95 of valve 78, port 52, passage 51 and pipe 50 to the working cylinder space 152, thus displacing the piston 151 to the left, liquid from the return cylinder space 153 exhausting through pipe 47, port 49, annular chamber 94 of valve 78, port 66, channel 65, port 67, annular space 34 of valve 80, port 63, channel 62, port 64, longitudinal grooves 25 in valve 79, and passage 157 to reservoir. The pump also supplies through channel 41, port 44, annular space 36 of valve 80, transverse bore 75, longitudinal bore 76, transverse bore 77, all in the valve 80, annular space 38 of valve 80, port 54, passage 57 and port 53 to valveoperating chamber 22 ; the passage 51 conveying pressure liquid by pipe 50 to the space 152 as described above, also communicates through port 56, annular space 38 of valve 80, port 54, passage 57 and port 53 with chamber 22 ; the pressure in chamber 22 acts on the piston 87 to hold the valve 78 in the position shown against the action of the spring 91. At the end of the working stroke of member 155, the valve 80 is moved by tappet gear (not shown) into its right-hand position, shown in Fig. 6, in which port 67 is covered by piston 27 of valve 80, so that exhaust from the return space 153 through 47, 49, 94, 66, 65 is stopped ; the passage 51 supplied from pump via 41, 42, 95, 52, and communicating through pipe 50 with working space 152 is put to reservoir through 56, 37, 60, 59, 61, 25, 157, this in effect byepassing the pump; 51 no longer communicates with 22, which is put to exhaust through 53, 57, 54, 38, 55, 156 ; supply from the pump no longer passes through 41, 44, 36, 75, 76, 77, 38, 54, 57, 53 to space 22, but instead passes by 41, 44, 35, 72, 73, 74, 33, 71, 68, 69, 70 to act on the piston 85, thus aiding the spring 91 to force the valve 78 to its right-band position, shown in Fig. 6. The pump delivery through 41, 42 now passes through 94, 49, 47 to the return cylinder 153 ; the working cylinder 152 is in communication through 50, 51, 56, 37, 60, 59, 61, 25, 157 with the reservoir, permitting the exhausting of said cylinder. At the end of the return stroke of member 155, the valve 80 is moved by tappet gear (not shown) into its left-hand position shown in Fig. 1; the space behind 85 is put to exhaust through 66, 65, 67, 34, 63, 62, 64, 25, 157; the pump supply to 153 is still maintained through 41, 42, 94, 49, 47, so that liquid is still discharged from 152 through 50 to 51 ; the communication between 51 and the exhaust through 56, 37, 60, 59, 61, 25, 157 being now closed, the displaced liquid from 51 passes through 56, 38, 57, 53 to chamber 22, the communication of this latter to reservoir through 53, 57, 54, 38, 55, 156 having been interrupted ; this displacement of liquid moves the valve 78 to the left against the action of the spring 91, as described in the parent Specification. If the machine part 155 has reached a stop or encountered excessive resistance, this displacement cannot take place. Reversal is ensured however, by the fact that the pump supply passes through 41, 44, 36, 75, 76, 77, 38, 54, 54, 57, 53 to chamber 22 to effect the movement of the valve 78 back to the position shown in Fig. 1. The central control slide 79 can be moved longitudinally to bring the annular groove 23 therein into register with the ports 64; with this setting, during the working stroke, liquid exhausting from the return side of the working piston through 47, 49, 94, 66, 65, 67, 34, 63, 62, 64 passes, not to reservoir by way of grooves 25 and conduit 157, but instead through annular groove 23 and longitudinal grooves 24, and port 43 into 41, i.e. is introduced into the pump delivery. The working speed of the piston is thus increased, with simultaneous reduction of the force acting on it. This setting does not affect the manner of working during the return stroke. To stop the operation of the machine, the central control slide 79 is rotated through 90‹, from either of its two longitudinal positions ; the pump delivery is then byepassed through 41, the port 43, the longitudinal grooves 25 in the slide 79, and conduit 157 to the reservoir.